Process for producing substituted or unsubstituted 2-phenyl-1.2.3.-triazole-4-carboxaldehyde

ABSTRACT

2-Phenyl-1.2.3-triazole-4-carboxaldehydes having the formula: ##STR1##are obtained by oxidizing a 2-phenylglycosotriazole having the formula: ##STR2## wherein R is hydrogen, halogen, methyl, carboxyl, a sulfonic acid group or the alkali metal salt thereof, n is 2 or 3, R&#39; is hydroxymethyl when n is 2 and is hydroxymethyl or methyl when n is 3, with an oxide of manganese such as manganese dioxide or manganese oxide in dilute sulfuric acid of 20 to 80 wt. % concentration at a temperature of 0° to 80° C. The oxidation reaction is carried out in a dispersed state for from 2 to 100 hours and the resultant aldehyde is separated from the reaction mixture by extraction with an organic solvent. The purity of the aldehyde thus obtained is higher than 85 wt. % and the yield is 40% to quantitative on the basis of 2-phenylglycosotriazole. The aldehyde can be further purified by convenient means.

Background of the Invention

1. Field of the Invention

This invention relates to a process for producing substituted orunsubstituted 2-phenyl-1.2.3-triazole-4-carboxaldehydes. The aldehydesare important intermediates for dyestuffs, fluoroescent brighteners andother organic compounds.

2. Description of the Prior Art

Methods of preparation of 2-phenyl-1.2.3-triazole-4-carboxaldehydes arealready known. The aldehydes are prepared through their oximes (JapanesePat. No. 708,447), or obtained by the oxidation of2-phenylglycosotriazoles using periodic acid as an oxidant (R. M. Hannand C. S. Hudson, J. Am. Chem. Soc., Vol. 66, Page 736 (1944)).

However, these prior art processes are very difficult to apply tocommercial production of the aldehydes for several reasons. For example,in the method for preparing the aldehydes through their oximes, theoximes are very difficultly available because many reaction steps arerequired to obtain the oximes from such a starting material as citricacid as follows: ##STR3## The intermediates in the above series ofreactions are unstable, and some of the reaction steps above areaccompanied by the evolution of such harmful gases as hydrogen cyanideor carbon monoxide, so that extreme caution and handling conditions arenecessitated for preparation of the oximes in this manner.

On the other hand, the method for obtaining the aldehydes by theperiodic acid oxidation of 2-phenylglycosotriazoles has the seriousproblem that the oxidant periodic acid is very expensive, and recoveryof unreacted periodic acid from the reaction waste is very difficult.

Lead tetraacetate and bismuthate salts are known to be useful oxidantsfor the oxidation of 1,2-glycols into the corresponding aldehydes, andthese oxidants can be also used for the oxidation of2-phenylglocosotriazoles to produce the corresponding aldehydes.However, the commercial application of these oxidants in the productionof the aldehydes is also very difficult because both lead tetraacetateand bismuthate salts are expensive and the recovery of unreacted leadtetraacetate or bismuthate salts from the reaction wastes is verydifficult, and because use of the lead compound is restricted forpurposes of prevention of environmental pollution.

On the other hand, oxides of manganese, for example, manganese dioxideor manganese oxide (trimanganese tetroxide) are well known oxidants forthe oxidation of the methyl group or the hydroxymethyl group to analdehyde group. However, it has not been known or disclosed that theseoxides of manganese can be successfully used for the oxidation of1,2-glycols to the corresponding aldehydes.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a processfor producing substituted or unsubstituted2-phenyl-1.2.3-triazole-4-carboxaldehyde having the formula: ##STR4##wherein R is a member selected from the group consisting of hydrogen,halogen, methyl, carboxyl, a sulfonic acid group or an alkali metal saltthereof.

The above object has been attained by the oxidation of a2-phenylglycosotriazole having the formula: ##STR5## wherein R has thesame meaning as that defined above in formula (I), n is 2 or 3, R' ishydroxymethyl when n is 2 and is methyl or hydroxymethyl when n is 3,with an oxide of manganese such as manganese dioxide or manganese oxidein dilute sulfuric acid.

The resultant aldehyde is separated from the reaction mixture byextraction with an organic solvent. Then, the organic solvent isdistilled away from the extract and the aldehyde is obtained. The thusobtained aldehyde can be further purified, if necessary, by a convenientpurification method for aldehydes such as the purification method with asodium bisulfite solution.

Description of the Preferred Embodiments

The 2-phenylglycosotriazoles which are used as starting materials forthe process of the present invention can be obtained by the triazolecyclization of glycosazones of formula (V) prepared from monosaccharidesof formula (III) and phenylhydrazines of formula (IV) as follows:##STR6## wheerein the meanings of R, R' and n in formulas (III), (IV)and (V) are the same as those defined for formula (II) hereinbefore.

Examples of the monosaccharides of formula (III) which can be employedin the present invention include D-glucose, D-mannose, D-galactose,L-arabinose, D-xylose and L-rhamnose. Examples of the phenylhydrazinesof formula (IV) include m-chlorophenylhydrazine,p-chlorophenylhydrazine, p-bromophenylhydrazine,p-methylphenylhydrazine, p-carboxyphenylhydrazine, sodiumphenylhydrazine-4-sulfonate and phenylhydrazine.

The structural formulas of the 2-phenylglycosotriazoles of formula (II)in which R is hydrogen are as follows: ##STR7##

The 2-phenylglycosotriazoles are not completely dissolved in the dilutesulfuric acid, and are presented for the oxidation reaction in thedispersed state in the acid. Therefore, the 2-phenylglycosotriazoles arepreferably finely pulverized by any convenient means before use so thatthe oxidation reaction will proceed smoothly.

The oxides of manganese useful as oxidant in the present invention aremanganese dioxide and manganese oxide. The amount of the oxide ofmanganese is preferably within the range of from 3 to 8 moles, morepreferably from 4 to 7 moles, per each 1 mole of thephenylglycosotriazole. The oxide is finely pulverized by any convenientmeans before use, if necessary or desired.

The concentration of the dilute sulfuric acid is generally within therange of from 20 to 80 wt. %, preferably from 30 to 50 wt. %. When usingsulfuric acid with higher concentrations, e.g. above 60 wt. %,undesirable side reactions tend to be accelerated, and with sulfuricacid of lower concentrations, e.g. lower than 20 wt. %, the rate of theoxidation reaction is undesirably reduced. The amount of the dilutesulfuric acid (in terms of 100% sulfuric acid) is generally within therange of 5 to 30 parts by weight, preferably 5 to 20 parts by weight,for each part of the starting 2-phenylglycosotriazole.

In the present invention, the 2-phenylglycosotriazole and oxide ofmanganese are dispersed in the dilute sulfuric acid and the mixture isvigorously stirred. Thus, the oxidation reaction proceeds smoothly inthe dispersed state. Suitable oxidation temperatures are generallywithin the range of from 0° to 80° C., preferably from 20° to 60° C. Theapplication of higher reaction temperatures causes undesirable sidereactions resulting in reduction of the yield.

The time required for the oxidation reaction is generally within therange of from 2 to 100 hours under such reaction conditions as describedabove with reference to the amount of the oxide of manganese, thereaction temperature and the concentration of sulfuric acid. A longerreaction time at a lower reaction temperature is preferred since it willdepress undesirable side reactions and produce the aldehyde in a higheryield. Within the above period of reaction time, the essentialconsideration that the oxidation of the 2-phenylglycosotriazole into thecorresponding aldehyde is substantially completed will be accomplished.

The resultant 2-phenyl-1.2.3-triazole-4-carboxaldehyde can be separatedfrom the reaction mixture as follows:

The reaction mixture is extracted with an organic solvent such as ether,petroleum ether, benzene, toluene, xylene, ethylene dichloride,trichloroethylene, tetrachloroethylene, etc., then the organic solventis distilled away from the extract by distillation, by distillationunder reduced pressure or by steam distillation. In this manner,2-phenyl-1.2.3-triazole-4-carboxaldehyde with a purity higher than 85wt. % can be obtained.

The obtained 2-phenyl-1.2.3-triazole-4-carboxaldehyde can be furtherpurified, if necessary, by any well known purification method foraldehydes, for example, purification with sodium bisulfite solution asdescribed in Example 1.

In Table 1, the melting points of several substituted and unsubstituted2-phenyl-1.2.3-triazole-4-aldehydes obtained according to the presentinvention are shown, although the invention is not limited thereto.

                  Table 1                                                         ______________________________________                                        R                Melting Point (° C.)                                  ______________________________________                                        H                 70                                                          CH.sub.3 (P)     80-82                                                        Cl (P)           121                                                          Cl (m)           88-89                                                        COOH (P)         276-278                                                      SO.sub.3 H (P)   >360                                                         ______________________________________                                    

After the aldehyde is separated from the reaction mixture by extraction,the unreacted oxide of manganese remaining dispersed in the reactionmixture is easily recovered by filtration.

Industrial advantages of the present invention include the fact that theoxides of manganese are readily and cheaply available and are recoveredquite easily from reaction mixture. The equivalent weights of the oxidesof manganese, especially the equivalent weight of manganese dioxide, aresmaller than those of oxidants employed by the prior art such as, forexample, periodic acid, lead tetraacetate or bismuthate salts, so thatin the present invention, it is possible to carry out the oxidation witha smaller amount of oxidant compared to the processes of the prior art.

Moreover, Mn++ is easily removed from the reaction waste water when thewaste water, containing sulfuric acid and Mn++, is neutralized with analkali and the resulting precipitate is filtered off. Thus, for example,waste waters containing only 0.38 ppm or 0.05 ppm of Mn++ are obtainedby neutralization with sodium hydroxide or by neutralization with lime,respectively.

The advantages described above are valuable facets of the presentinvention with regard to prevention of environmental pollution.

The present invention will be particularly illustrated by the followingnon-limiting examples.

EXAMPLE 1

A mixture of 5.3 g. of 2-phenylglucosotriazole, 100 ml. of 50 wt. %sulfuric acid and 10.4 g. of manganese dioxide powder (75 wt. % purity)were stirred at 40° C. for 5 hours. Then, the reaction mixture wasdiluted with 100 ml. of water and was extracted with 100 ml. of ether.The ether was distilled away from the extract and the residue wasdissolved in 50 ml. of boiling sodium bisulfite water solutioncontaining 5% by weight sodium bisulfate. The solution was filtered toremove insoluble material and the resultant filtrate was basified with10 ml. of 10% by weight aqueous sodium hydroxide to cause precipitation.The resultant precipitate was separated from the solution by filtration,washed with 50 ml. of water and dried. Thus,2-phenyl-1.2.3-triazole-4-carboxaldehyde was obtained in 70% yield onthe basis of 2-phenylglucosotriazole.

EXAMPLE 2

Example 1 was repeated except that the concentration of sulfuric acidand the reaction temperature were 65 wt. % and 20° C. instead of 50 wt.% and 40° C., respectively. 2-Phenyl-1.2.3-triazole-4-carboxaldehyde wasobtained in a 40% yield, and at the same time the formation of aresinous by-product was observed.

EXAMPLE 3

Example 1 was repeated except that the concentration of sulfuric acidand the reaction temperature were 30 wt. % and 60° C. instead of 50 wt.% and 40° C., and that finely pulverized 2-phenylglucosotriazole wasused. 2-Phenyl-1.2.3-triazole-4-carboxaldehyde was obtained in aquantitative yield.

EXAMPLE 4

A mixture of 5.3 g. of 2-phenylglucosotriazole, 100 ml. of 45% sulfuricacid and 10.4 g. of manganese dioxide powder (75 wt. % purity) werestirred at 30° C. for 48 hours. Then, the reaction mixture was dilutedwith 100 ml. of water and was extracted with 50 ml. of benzene. Afterevaporation of benzene from the extract,2-phenyl-1.2.3-triazole-4-carboxaldehyde with purity higher than 85 wt.% was obtained in 80% yield. The thus obtained aldehyde, without furtherpurification, can be employed for practical uses for which the purifiedaldehyde is commonly employed.

EXAMPLES 5-7

Example 1 was repeated except that 2-(P-chlorophenyl)-glucosotriazole,2-(P-methylphenyl) glucosotriazole and 2-(P-carboxyphenyl)glucosotriazole were respectively used instead of2-phenylglucosotriazole. Thus,2-(P-chlorophenyl)-1.2.3-triazole-4-carboxaldehyde,2-(P-methylphenyl)-1.2.3-triazole-4-carboxaldehyde and2-(P-carboxyphenyl)-1.2.3-triazole-4-carboxaldehyde were obtainedrespectively in similar yields as that of2-phenyl-1.2.3-triazole-4-carboxaldehyde in Example 1.

EXAMPLES 8-11

Example 1 was repeated except that 2-phenylgalactosotriazole was usedinstead of 2-phenylglucosotriazole, and2-phenyl-1.2.3-triazole-4-carboxaldehyde was obtained in a similar yieldto that in Example 1. Example 1 was further repeated except that2-phenylxylosotriazole,2-phenylarabinosotriazole and2-phenylrhamnosotriazole were respectively used instead of2-phenylglucosotriazole, and that the amount of manganese dioxide was 8g. instead of 10.4 g. 2-phenyl-1.2.3-triazole-4-carboxaldehyde wasobtained in each example in a similar yield to that in Example 1.

As described hereinbefore, the 2-phenyl-1.2.3-triazole-4-carboxaldehydeproduced according to the present invention are important intermediatesfor dyestuffs, fluorescent brighteners and other organic compounds. Forexample, such compounds as ##STR8## are valuable fluorescent brightenersfor polyester fibers.

What is claimed is:
 1. A process for producing substituted orunsubstituted 2-phenyl-1.2.3-triazole-4-carboxaldehyde having theformula: ##STR9##wherein R is hydrogen, halogen, methyl, carboxyl,sulfonic acid group or alkali metal salt thereof, which comprisesoxidizing 2-phenylglycosotriazole having the formula: ##STR10##wherein Rhas the same meaning as that defined above, n is 2 or 3, and R' ishydroxymethyl when n is 2, and is methyl or hydroxymethyl when n is 3,in dilute sulfuric acid with an oxide of manganese selected from thegroup consisting of manganese dioxide and manganese oxide.
 2. Theprocess according to claim 1 wherein said 2-phenylglycosotriazole is2-phenylglucosotriazole.
 3. The process according to claim 1 whereinsaid oxide of manganese is manganese dioxide.
 4. The process accordingto claim 1 wherein said dilute sulfuric acid has a concentration of from20 to 80 wt. %.
 5. The process according to claim 4 wherein said dilutesulfuric acid has a concentration of from 30 to 50 wt. %.
 6. The processaccording to claim 1 wherein the oxidation is carried out within atemperature range of from 0° to 80° C.
 7. The process according to claim6 wherein the oxidation is carried out within a temperature range offrom 20° to 60° C.
 8. The process according to claim 1 wherein saidoxide of manganese is present in an amount of from 3 to 8 moles per moleof 2-phenylglycosotriazole.
 9. The process according to claim 1 whereinthe reaction mixture is extracted with an organic solvent and theorganic solvent is then removed to yield the substituted orunsubstituted 2-phenyl-1.2.3-triazole-4-carboxaldehyde of high purity.10. The process according to claim 1 wherein the oxidation is conductedin the dispersed state.